Sealer head mechanism of an automatic strapping machine



United States Patent [72 1 Inventors Jack J. Dalton [56] References Cited Pittsburgh; UNITED STATES PATENTS [21 I A l N ,2'; Pennsy'vania 1,712,037 5/1929 Halter 140/914 PP- 1.805,?91 I931 T t .100 33 [221 Filed Oct-14,1968 tea I a Patented Dec. 8, 1970 Primary Exammer-Lowell A. Larson [73] Assignee Cyclops Corporation Atlorney- Webb, Burden, Robinson & Webb Allegheny Strapping Division, Pittsburgh, 522232321: of Pennsylvania ABSTRACT: A sealer for an automatic strapping machine in which a frame carrying a shdable upper die and a stationary lower die is pivotally mounted to a stationary main plate. A pneumatically actuated toggle joint is mounted in the frame, [54] SEALER E i ggg OF AN AUTOMATIC one link thereof being connected to the pivotal mounting STRAiPPIND Fl between the main plate and the frame and the other link being 6 ch raw connected to the slidable upper die. A stop means prevents [52] [1.8. CI 140/932, movement of the toggle joint relative to the main plate after /33 the toggle joint has passed through the alined position. The [5| lnt.Cl. B2lf 9/02 continuing force on the knee of the toggle joint causes the [50] Field of Search /93, frame to pivot about the main plate whereby the lower die is t 93.2, 93.4; i0O/29 30, 33 removed from beneath the sealed strapping.

Hi I I 34 35 l2 Pmmenm 8I97B V H 3545499 SHEET 1' 0F4 Jack J.D0Hon y John J. Linehan MM mww% THEIR ATTORNEYS V mm PATENIED DEC 8 new lNVlzN'H 1R3 Jack J. Dalto John J. Lineh THEIR ATTORNEYS IN VIfN'I'URs By John J. Linehan WM M Mama-L Jack J. Dalton THEIR ATTORNEYS I SHEET [1P4 ihl. 2O 23 35 62 INVLNTORS Jack J. Dalton BY John J. Linehon MMMg'wd/l THEIR ATTORNEYS SEALER HEAD MECHANISM OF AN AUTOMATIC STRAPPING MACHINE Our invention relates to a sealer for an automatic strapping tool. More particularly, it relates to a sealer by which overlapped lays of strapping material are interlocked by die-cut notching. In the operation of conventional strapping tools, a continuous strip of strapping is fed around the object to be strapped and two lays of the strapping are overlapped. The strapping is tensioned and the overlapped lays are fastened. The lays may be fastened by 'placing a separate sealing member around the lays or by die-cut notching which interlocks the two overlapped lays of strapping. In the latter method the overlapped lays are positioned between an upper and lower die which are brought together to provide the interlocking crimp. After the dies are separated, the lower die must be removed from its position between the joined strapping and the object being strapped. a i

l The mechanisms necessary for interlocking the overlapped lays of strapping are less complex than those required if a separate seal is used. However, heretofore, it has been necessary to provide a separate mechanism, involving individual switching, valving and actuating means, in order to remove the lower die from between the strapping and the object being strapped. Thus,all advantage in initial costs, maintenance and repair parts is lost. Our invention eliminates the separate removal mechanism entirely, utilizing the same action and mounted to a stationary main plate. Mating dies, anupper slidable die and a lower stationary die, are mounted in the frame. A toggle'joint has one'link pivotally mounted to the main plate and the frame and the other link connected to the upper die. The links are dimensioned so that when in line the upper die will be forced against the lower die with a sealing force. Means are provided for applying a force to the connection between the two links of the toggle joint. The means is capable of applying sufficient force to move the links from an angular position to an beyond the: alined position. A stop means is positioned to prevent further movement of the toggle joint relative to main plate after passage through the alined position whereby the continuing force pivots the frame about the main plate. t a

In the accompanying drawings,v we have shown one preferred embodiment of our invention in which:

FIG. 1 is a schematic illustration of a complete strapping unit;

FIG. 2 is a longitudinal section through our sealer showing the position of the elements prior to the start of the sealing cysealer at the time in the cycle when the maximum stroke of the piston has been completed and the head stripped from the sealed strapping.

strapped are inserted. A source 8 of strapping is positioned ad jacent the unit. Although the strapping unit is particularly adapted to steel strapping, it may be sued with other types of strapping materials. Feed means 4 includes a drive wheel 13 and an idler wheel 13'. Rotation of the drive wheel clockwise feeds strapping from source 8 to path 9 of the track assembly and clockwise around the path, through gripper means 5 and through sealer 6. Thelead end of the strapping material passes through the sealer a second time so that two lays of the strapping l0 overlap in the sealer between upper cripping die 11 and lower crimping die' 12. As the lead end of the strapping The overall assembly of a strapping unit in which our invention may be incorporated is shown in FIG. 1. A frame (not shown) supports a head 1 and a track 2. The head includes a main plate 3 on which feed, means 4, gripping means 5 and sealer 6 are mounted. A track switch (not shown) is mounted on the main plate between the gripper and the sealer. The track assembly 2 provides a continuous path 9 for strapping material around an opening 7 into which the objects 7' to be material passes between the dies at second time, the track switch stops the drive wheel. Filling the track with strapping material is the first step in preparing the unit for use. However, in an automatic or semiautomatic cycle, it is usually the last step in the sequence.

After the track 2 is filled with strapping and the object to be strapped inserted in opening 7, the gripper assembly 5 is energized causing two grippingfingers 14 to secure the second lay of strapping against a fixed shear edge 39 (see FIG. 3) separating the opposite ends of the strapping. This restraint secures the overlapped lay of strapping in between the crimping dies. Simultaneously, the drive wheel 13 is reversed. The counterclockwise rotation of the drive wheel extracts the strapping 10 from a spring-loaded (not shown) restraint of the tack assembly 2 and lays it snugly around the object to be strapped. Continued rotation of the drive wheel tensions the strapping about the 'object. When an ultimate desired tension is secured in the strapping (between the gripper finger l4 and the drive wheel 13), a signal is given which initiates the sealing action.

I The sealer '6 in which our invention resides is pivotally mounted to stationary main plate 3. It has a frame which con sists of a top plate 3l,side' plates 30 whichare bolted to the top plate, a cylinder body 29 which isbolted to the sideplates, and a bottom plate 32 fastened to the main plate 3. Pin 26 extends through extension plates 25 andsideplates 30 pivotally connecting the frame to the main plate.

The two lays of strapping are fastened to each other by diecut notching which interlock the two lays. This is accomplished by a pair of mating dies 11 and 12.'Upper die 11 is mounted in a crosshead piston 27 which is slidably mounted in cylinder body 29. Lower die 12 is mounted on a sealer foot 35, which is affixed to a projection of the cylinder body and extends under the open lower end of cylinder body 29 and under the crosshead piston. Downward movement of the crosshead piston brings the two die members into contact whereby an interlocking seal can be made between the two lays of strapping positioned between the die members.

Movement of the crosshead piston 27 is controlled by a toggle joint mounted within the frame. The toggle joint is composed of a pair of identical upwardly extending links 22 and a pair of identical downwardly extending links 23, all of which have one end pivotally mounted on a pin 24. We prefer to have the two downwardly extending links positioned inside the two upwardly extending links on the connecting pin 24 (see FIG. 3). The downwardly extending links 23 are connected at the other end to the crosshead piston 27 by pin 28. The other end of the upwardly extending links 22. are connected to pin 26 about which the entire frame is pivotally mounted as described above. As is well-known to those skilled in the art, the links which make up the two arms of a toggle joint are not in line so that a force applied to the knee or connection between the two arms will force the: arms to come into alinemerit which in turn exerts a force on the parts to which the other end of the two arms are connected. In our structure this latter force drives the crosshead piston downwardly so that the upper die carried by the piston mates with the lower die, piercingthe strapping positioned between the upper and lower dies thereby interlocking the two lays of strapping and forming a firm seal. t

The force which straightens the links is applied to the connection between the links by a power cylinder 15 which is mounted on the rear end of the frame behind main plate 3 by bolts51 which fasten the front wall 52 of the cylinder to top plate 31 and bottom plate 32. The power cylinder includes a piston 16 connected to piston rod 17 which extends through the forward wall 52 of the cylinder and through an opening in the main plate. The rod is connected by two links to the knee of the toggle joint. One end of each link 21 is pivotally connected to rod 17 by pin and the other end of each link is pivotally connected to pin 24 which connects the links 22 and 23 forming the toggle joint.

7 The piston 16 is biased by spring 19 toward the rear wall 53. A tap 18 in the rear wall is adapted to be connected to a source of air under pressure. O-rings or other suitable gasket means (not shown) will be provided on the periphery of the piston to prevent leakage of the air around the piston. Thus, the admission of air under pressure to the cylinder will cause piston 16 and piston rod 17 to move to the right compressing spring 19 and straightening the toggle joint.

The cylinder and piston rod are dimensioned so that the piston not only causes the links of the toggle joint to straighten out and effectuate a seal as described above but also to move beyond the alined position (see FIG. 5). As the piston forces the links past the alined position, the force on crosshead piston 27 is removed as it moves away from the interlocked strapping.

A stop member 36 is attached to the main plate and extends forwardly from the plate between the two upwardly extending links 22 and terminating in a downwardly extending projection 60 positioned in a vertical plane which is forward of the plane of the links when alined. A stop pin 37 extends between the two upwardly extending links at a position to contact projection 60 after the piston .has forced the links beyond the alined position as shownin FIG. 5. The stop means prevents further movement of the toggle joint relative to the main plate.

Continued forward movement of the piston forces the frame of the sealer to pivot clockwise about pin 26. This movement pulls sealer foot 35 outfrom under the interlocked lays of strapping as shown in FIG. 6. Since the strapping is under tension, it moves from its original position shown in dotted lines 61 in FIG. 6 to the package surface as shown in solid lines 62 in FIG. 6, thereby clearing a path for the sealer foot to return to its original position.

It is an important feature of our sealer that the sealer foot cannot be removed from beneath the strapping until after the full sealingforce has been applied.

When the piston has reached its extreme position shown in FIG. 6 the pneumatic valving is reversed and the piston re'tumed toits original position by spring 19. Two springs 33 each having one end fastened to the main plate by pin 34 and another end fastened by a similar pin 34 to the front wall 52 of the power cylinder return the entire frame to its original position. An adjusting screw 38 extending from the front wall of the cylinder toward the main plate regulates the return counterclockwise movement of the frame and positions the frame relative to the main plate for commencement of the next strapping cycle. A stop 38' is countersunk into the main plate 3. The return counterclockwise movement is stopped when the adjusting screw abutsthe stop; the amount of counterclockwise movement can be adjusted by adjusting the distance which the screw 38 extends toward the main plate. Stop 36 can also be made adjustable, for example, by making it in two pieces connected by bolts which can be adjusted to change the position of the forward segment having projection 60 relative to the main plate.

In order to provide adjustment for varying gauges of strapping to be interlocked, pin 26 is formed with an eccentric portion 26' between the two upwardly extending links 22 which permits proper spacing of the crimping dies (see FIG. 3). On one end, pin 26 is cylindrical in shape extending through one extension plate 25, bushing 45 and sideplate 30. The portion 26' of the pin extending between the two links 22 is eccentric having a greater radius on one side than on the other. The other end'of pin 26 is shaped to conform with opening 43 in washer 42 through which it extends. Washer 42 is fastened to extension plate 25 by lock screw 41 and can rotate within the confines of opening 44. As the washer moves about fixed lock screw 41, the pin 26 rotates changing the position of the eccentric portion 26' of the pin. This, in turn, raises or lowers upwardly extending links 22 which are connected to pin 26 and thus the distance between the upper and lower dies.

Pin 28 which connects links 23 to crosshead piston 27 has a flattened portion 28 which extends beyond one side of cylinder body 29 to a position directly above movable shear blade 40 (see FIG. 3). When links 23 force piston 27 downward to effectuate the seal, portion'28' of pin 28 contacts shear blade 40 forcing it downward and the upper lay of strapping material is cut between shear blade 40 and fixed shear edge 39. The shear blade is spring biased and returns to its original position when pin 28 moves out of contact with it.

Although we have described a toggle joint in which each arm is composed of a pair of links, it should be understood that a single link could be used for each arm. Similarly, a single link could be used to connect the piston rod to the knee of the toggle joint.

While we have herein shown and described a preferred embodiment of our invention, it is recognized that departures may be made therefrom, but that the invention will be accorded the full scope of the claims so as to embrace any and I all equivalent devices.

We claim: 1. A sealer for a strapping unit in which two lays of strapping material are fastened by die-cut notching comprisii. the second link of the toggle joint being pivotally connected to the upper slidable die; and

iii. the two links of the toggle joint being dimensioned so that when in line the upper die will be forced against the lower die with a sealing force;

F. means for applying a force to the connection between the two links of the toggle joint, said means being capable of applying sufficient force to move the links from an angular position to and beyond the alined position; and

G. stop means positioned'to prevent further movement of the toggle joint relative to the main plate after passage through the alined position whereby continued application of the force pivots the frame about the main plate.

2. A sealer as set fort in claim 1 wherein the means for applying a force to the connection between the two links of the toggle joint includes:

A. a power cylinder mounted on the rear end of the frame;

B. a piston slidably mounted in the cylinder; and

C. a piston rod having one end attached to the piston and the other end pivotally mounted to the connection between the two links of the toggle joint.

3. A sealer as set forth in claim 1 wherein the stop means includes:

A. a stop pin attached to one link of the toggle joint and extending substantially normal to the link; and

B. a stop member attached to the main plate an extending forwardly from the plate, said stop member terminating in a projection positioned to contact the stop pin after the toggle joint has passed through the alined position.

4. A sealer as set fort in claim 1 wherein the link of the toggle joint is pivotally mounted to the main plate and to the frame by an eccentric pin adjustable to change the distance between the mating dies in the alined position, thus enabling strappings of various gauges to be interlocked between the dies.

6. A sealer as set forth in claim 2 wherein at least one spring is positioned within the power cylinder to resist the movement of the piston and to urge the piston rod away from the toggle joint and into said cylinder.

:IJNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 545, 499 Dated December 8, 1970 Inventor(s) Jack J. Dalton and John J. Linehan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 Line 36 --main plate 3. should read "cylinder body. Column 2 Line 36 before "Pin 26-- insert --Two spaced extension plates 25 are fastened to the main plate 3. Column 4 Claim 3 Line 66 --a.nshould read -and--.

Signed and sealed this 30th day of May 1972.

(SEAL) Attest:

EDWARD M1. FLETCHER,JR. ROBERT HALK At testing Officer Commissioner of Patent 

